1. Field of the Invention
The present invention relates to a molding apparatus for molding semiconductor electronic components in a sealing fashion and, in particular, a molding apparatus which, upon sealingly molding semiconductor electronic components with a thermosetting resin, can discharge air, or air and thermosetting resin, trapped at or near the mold cavities via a groove which is provided on the surface portion of a pair of molding body halves at a location facing an unnecessary lead of those lead frames.
2. Description of the Related Art
FIGS. 1 and 2 show a conventional molding apparatus for sealingly molding semiconductor electronic components. In FIG. 1, molding body half 7 as shown in perspective view is of such a type that semiconductor electronic components ar held each within mold cavity 8 with the semiconductor electronic component electrically connected to the forward ends of leads 3 of lead frame 2 to allow them to be obtained as resin-sealed products 1. Lead frame 2 has, in parallel fashion, leads 3 made up of a pair of leads and unnecessary lead 4 which is eliminated upon the completion of a molding operation. Leads 3 and unnecessary lead 4 are coupled by a tiebar 5. Subsequent to disposing the semiconductor electronic component in place within mold cavity 8 a molten thermosetting resin is flowed via resin inlet hole 10 of molding body half 7 into the mold cavity with the other molding body half placed on the first-mentioned molding body half. In this case, the semiconductor electronic component is sealed with the resin such that the associated leads are connected to the semiconductor electronic component. Air outlet groove 9 is provided along leads 3 in the molding body half such that it is located at a place opposite to resin inlet hole 10. Upon the sealing of the semiconductor electronic component with the resin, air trapped within cavity 8 is discharged via groove 9 to the outer air. The discharge of the air at that time often involves a simultaneous discharge of some of the molten resin so that the resin is deposited partially on leads 3 as shown in FIG. 2. The resin, if deposited on tiebar portion 5 only, can be removed at a subsequent lead separation step following the aforementioned resin sealing step, but, if deposited on leads 3 of the lead frame, any extra separation step is required during the manufacture of semiconductor electronic components.